The present invention relates to nonwoven materials produced from continuous tow bands, and to apparatuses, systems, and methods related thereto.
Nonwoven material is a term of art that refers to a manufactured sheet, batting, webbing, or fabric that is held together by various methods. Those methods include, for example, fusion of fibers (e.g., thermal, ultrasonic, pressure, and the like), bonding of fibers (e.g., resins, solvents, adhesives, and the like), and mechanical entangling (e.g., needle-punching, hydroentangling, and the like). The term is sometimes used broadly to cover other structures such as those held together by interlacing of yarns (stitch bonding) or those made from perforated or porous films. The term excludes woven, knitted, and tufted structures, paper, and felts made by wet milling processes.
Nonwoven materials can be produced from carding processes that convert bales of staple fibers into mats that are needlepunched or hydroentangled to produce the nonwoven materials. Staple fibers are finite in length (approximately 7 centimeters in length) that during carding are spread into a uniform web. In the final steps of carding, a resin bonding treatment is typically included to enhance the robustness of the final nonwoven material, e.g., making the nonwoven material durable to washing.
During the carding process, staple fibers which are shorter may not be able to be carded by the carding apparatus and drop to the floor thereby creating waste. In some instances, recycling of the shorter stable fibers is performed to minimize waste.
Further, during the carding process, stable fibers may become airborne thereby increasing mechanical problems and health risk. Airborne fibers may collect in the equipment leading to increased maintenance and possible downtime. Further, airborne fibers pose inhalation and dermal irritation risks to workers.
Because of the significant investment in capital equipment for carding and health issues associated with processing bales of staple fiber, the production of nonwoven materials from tow bands has been of interest to one skilled in the art. As used herein, the terms “continuous tow band” and “tow band” may be used interchangeably to refer to a collection of continuous (e.g., indefinite or extreme length) fiber filaments without defined twist usually held together with a crimp and/or tackifier. It should be noted that tow bands may be of any cross-sectional shapes including, but not limited to, circular, substantially circular, ovular, substantially ovular, rectangular, substantially rectangular, planar, and substantially planar.
Producing nonwoven materials from continuous tow bands potentially increases the production speed of nonwoven materials in two ways. First, tow bands can be processed on the order of 650 meters per minute while bales of staple fibers can be run at a max speed of about 400 meters per minute. Second, bales of tow bands have more material than bales of staple fibers, which reduces the frequency of switch bales relative to the production volume of nonwoven materials. However, tow bands are typically produced with maximum widths of about 15 cm to about 60 cm depending on the composition of the tow band filaments. As some nonwoven materials need to be produced with widths of meters, the use of tow bands for the production of nonwovens has been limited.
Apparatuses to bring together tow bands to produce nonwoven materials similar in width to nonwoven material produced by carding would be of benefit to one skilled in the art for a plurality of reasons.